Fluid heater for semiconductor device

ABSTRACT

A fluid heater for a semiconductor device is provided to uniformly heat a gas, for thereby improving uniformity and speed of gas reaction and thus increasing the yield of semiconductor device fabrication. The fluid heater includes a main heater of a helical shape formed of a thermal conductor having various radii; a transparent tube, in which the main heater is located, having a plurality of holes at a lower portion thereof; an internal vessel disposed at an outer side of the transparent tube and having a plurality of holes at an upper portion thereof; an external vessel located at an outer side of the internal vessel; flanges placed on the external vessel, the internal vessel and the transparent tube and connecting a fluid inflow tube and the transparent tube and an external heater disposed at an outer wall of the external vessel. Here, the main heater is fabricated in a helical shape which has various radii, so that the fluid is evenly heated by a vortex generated by which the fluid passes through the main heater and also the fluid is heated by direct contact with the heater, thereby having an effect of increasing a temperature of the fluid up to a sufficiently high temperature, for example, a temperature above 600° C.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for fabricating asemiconductor device, and more particularly to an apparatus for heatinggases for a semiconductor device that heats gases, which are introducedto a thin film forming device, an oxidation device, an etching device ora reaction furnace, to a fluid state.

2. Description of the Conventional Art

In a semiconductor device such as a thin film forming device or anetching device for fabricating a semiconductor device, a main gas whichis a process source (a fluid substance participant of reaction on awafer) and subsidiary gases such as a carry gas which carries theprocess source to a reaction furnace and an oxygen gas are introducedinto a vaporizer (not shown), respectively maintaining a temperatureunder 100°, mixed and vaporized therein, then injected as the gaseousstate into a chamber through a gas injector 1, and activated byreceiving a heat energy or other energy on a wafer W, thereby having areaction. Numerals 2 and 3 in FIG. 1 are a heat supplying unit and a gasdischarge line, respectively.

When forming a thin film using the thin film forming device shown inFIG. 1, it is desirable to maintain a temperature of the wafer to be lowand to increase a deposition rate of the thin film. To satisfy suchrequirements, support in various ways is necessary in the aspect of ahardware of a semiconductor device, and one of the various ways thereforis to introduce a gas in a heated state into the reaction furnace.

When the process sources, the main gases of the reaction, are requiredto be heated, there is provided a method of heating a process sourcetank, in which the process sources are stored, and also introducing theprocess gases, which are in a heated state at a temperature of about100° C. or below, into the reaction furnace by winding a heater at anouter wall of a tube which is a transfer path of the process source.Among various types of conventional methods of heating a tube, followingthree types are the most typical methods thereof.

A first type employs a method of heating a gas tube by simply winding aheater at an outer wall of a tube up to 300° C.

As shown in FIGS. 2A and 2B, a second type of the tube heating method isto supply the heat energy to a fluid substance with a small space,wherein the fluid substance is heated while flowing in a tube 20 bywinding a heater 21 at an outer wall of the spring-type heater 21.

As shown in FIG. 3, for a third type of the tube heating method, thereis provided a heating vessel 31 disposed in a middle of a tube 30 and asmall heating bottle 32 installed in the heating vessel 31, for therebyheating a gas in a direct contact method, the tube 30 and the heatingvessel 31 being connected with a flange 33.

Now, the heating operation of the conventional art will be described.

In the heating operation employing the first type, a fluid heatermaintains or heats a temperature of a process source gas with indirectheating through the tube by winding the heater at the tube to supply theheat energy to a fluid substance which flows in the linear tube.

In the heating operation employing the second type, the band heater 21is provided at the outer wall of the spring-type role tube 20, therebyheating the process gas using the relatively small space. Here, theheating method applied in the second type is an indirect heating methodin which the heat energy produced in the band heater 21 is transmittedto the roll tube 20 and then to the process source.

Lastly, the heating operation of the third type employs the heatingdevice of an in-line type, in which the process source is introducedinto the heating vessel 31 from the tube 30, so that the process sourceis heated while passing through the heating bottle 32 and then flowsinto a reaction furnace through the tube 30.

However, the conventional process source heating methods using the tubehave problems.

The method of indirectly heating the process source flowing in the tubesuch as in the first or second type has a problem in that since theprocess source is heated through the tube which is a heat transmittingmedium, temperature gradient of the process source can be incurred anduniformity of the temperature of the process source is poorly achieved.Also, there is another problem in which the maximum heating temperatureis limited at about 300° C. Thus, it is required to develop a hardwareapparatus which uniformly controls the temperature of the gas, improvesheat efficiency of the heater, and increases the maximum heatingtemperature.

Also, when applying the tube heating method of the third type, it ispossible to solve the problem in which the maximum heating temperatureis low in the first and second types due to the indirect heating method.However, the temperature uniformity is poorly achieved because oftemperature difference the process source which flows contacting theheating bottle in the heating vessel and the process source which flowsat a wall side of the heating vessel without directly contacting theheating bottle.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a fluid heater for asemiconductor device which obviates the problems and disadvantages inthe conventional art.

An object of the present invention is to provide a fluid heater for asemiconductor device that prevents a process source from previouslyreacting or liquefying before being introduced into a reaction furnaceand obtains temperature uniformity of the process source so that fluidreaction rapidly and uniformly occurs on a wafer in the reactionfurnace, and accordingly semiconductor devices fabricated in thereaction furnace have improved reliability and yield.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is provided a fluid heater for a semiconductor device which heatssubsidiary gases to a fluid state to heat a gas for a semiconductordevice which increases a temperature of a process source by maintaininga temperature of a process source which is a main gas at about 100° C.using a heating device which has the same configuration as in theconventional art and heating a carry gas or other subsidiary gases atleast at a temperature of 600° C., thereby mixing the process sourcewith the heated carry gas or other subsidiary gases in a vaporizer forvaporizing the process source in a liquid state, for thereby increasingthe temperature of the process source.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a schematic cross-sectional vertical view of a reactionfurnace for fabricating a semiconductor device;

FIGS. 2A and 2B are a side view and a plan view, respectively, of aconventional gas heating device for a semiconductor device;

FIG. 3 is a schematic cross-sectional vertical view of a anotherconventional gas heating device for a semiconductor device;

FIG. 4 is a schematic diagram of a gas heating device according to afirst embodiment of the present invention;

FIGS. 5A and 5B are a side view and a plan view, respectively, of a mainheater in FIG. 4;

FIG. 6 is a side view of a transparent tube in FIG. 4;

FIG. 7 is a side view of an internal vessel in FIG. 4;

FIG. 8A is an external heater disposed at an outer wall of an externalvessel;

FIG. 8B is another example of an external heater disposed at an outerwall of an external vessel; and

FIG. 9 is a schematic diagram of a fluid heater according to a secondembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

If process sources are excessively heated, the process sources may bereacted before arriving at a reaction furnace. Accordingly, in thepresent invention, there is applied a method of heating subsidiary gasessuch as a carry gas or an oxide gas at a temperature of about 600° C. orabove and mixing the heated subsidiary gases with process sources at atemperature of 100° C. or below in a vaporizer (not shown), instead ofheating the process sources a high temperature and introducing the gasinto the reaction furnace. Thus, since there is required a method ofheating the subsidiary gases over 600° C., according to the presentinvention provides a gas heating device for a semiconductor device whichheats the subsidiary gases to a fluid state. Here, the carry gas istransmitted to a reaction unit in which the carry gas is mixed with theprocess sources and thereby reacts before flowing into the reactionfurnace, the carry gas preventing the process sources from pre-reactingbefore arriving at a wafer.

The gas heating device for the semiconductor device according to thepresent invention will be described with respect to the accompanyingdrawings. Since the subsidiary gases such as the carry gas maintain afluid state and also remain in the fluid state before flowing into thereaction furnace, the gas heating device for the semiconductor deviceaccording to the present invention means a device for heating afluid-state gas before it becomes a gaseous state, that is a fluidheater. Accordingly, the fluid heater will be referred as the gasheating device according to the present invention.

FIG. 4 is a schematic diagram of a gas heating device according to afirst embodiment of the present invention.

As shown therein, 401a is an inflow tube wherein a fluid flows to a gasheating device 400, and 401b is a discharge tube wherein the fluidheated by the gas heating device 400 flows. The fluid (a subsidiary gas)heated in the gas heating device 400 flows into the vaporizer of anapparatus for fabricating a semiconductor device through the dischargetube 401b and mixes with a main gas.

The gas heating device 400 for the semiconductor device is disposedbetween the inflow tube 401a and the discharge tube 401b. Particularly,an external vessel 403 is disposed in between the tubes 401a and 401b,and a flange 415b is provided on the external vessel 403. Here, theflange 415b is detachable from the external vessel 403 for easilycleaning the fluid heater.

While, an internal vessel 405 is disposed in the external vessel, beingspaced from a wall and a bottom thereof, a top portion of which is fixedto the flange 415b. A support 407 is placed on a bottom of the internalvessel 405 and a transparent tube 409 which is formed of quartz whichhas high thermal conductivity is disposed on the support 407 in theinternal vessel 405.

The support provided on the bottom of the internal vessel 405 is formedof ceramic or quartz, which is refractory and has high thermalconductivity, and supports the transparent tube 409. Thus, the support407 is heated by radiant heat supplied from a main heater 411 of thetransparent tube 409. The heated support 407 transmits heat to the fluidin the external vessel 403. An upper portion of the transparent tube 409is also fixed to the flange 415b. Further, another flange 415a isdisposed on the flange 415b, and the flanges 415a and 415b are fixed bya screw 416, for thereby preventing the fluid flowed into the externaland internal vessels from being discharged. In addition, the flange 415ais connected with the inflow tube 401a.

Further, the main heater or an internal heater 411 is disposed in thetransparent tube 409. The heater 411 is a helical thermal conductor andthe radius of the helical thermal conductor varies in sequence, forexample, a long radius, followed by a medium radius, and then a smalland the its pattern repeating itself (See FIG. 5A and 5B). Thus, sincethe main heater 411 has various radii, fluid can be evenly heatedwhether flowing in a center of the heater 411 or at the edge thereof.Also, a vortex, which is generated by the fluid passing through thehelices of the main heater 411, enables the fluid to be well mixed andthus no the temperature gradient of the fluid flowing in the transparenttube 409 is incurred, thereby improving the fluid temperatureuniformity.

To maintain a temperature of the fluid heated by the main heater 411, anexternal heater 413 is disposed around the external vessel 403. Further,a heat shield material 421 is provided at an outer side of the externalheater 413 to increase the heat efficiency of the external heater 413.Plate heaters 419 are provided between the heat shield material 421 anda bottom of the external vessel 403 and between the heat shield material421 and the flange 415b, respectively, for thereby preventing the heatedfluid from being cooled down, and a line heater 435 is provided alongthe tubes 401a and 401b to minimize heat loss of the heated fluid.

A main heater terminal 412 is connected with an end of an upper portionof the main heater 411 to supply power to the main heater 411 andconnected with a first power controller 423. A thermocouple which is afirst temperature detector 425 is disposed next to the main heaterterminal 412 and detects a temperature of the main heater 411, the firsttemperature detector 425 being connected with a first temperaturecontroller 427 which is connected to the first power controller 423. Amain system control device, which will be described later, commands thefirst temperature power controller 427 to increase the temperature ofthe main heater 411 and accordingly the first temperature powercontroller 427 computes power volume for increasing the temperature ofthe main heater within a predetermined range and applies a signal to thefirst power controller 423, which supplies power to the main heater 411in accordance with the signal outputted from the first temperature powercontroller 427, so that the temperature of the main heater 411increases.

A second temperature detector 429 is provided between the externalvessel 403 and the bottom of the internal vessel 405 to detect atemperature of the fluid flowing between the internal vessel 405 and theexternal vessel 403, that is, the temperature of the fluid heated by thefluid heater before being discharged. The temperature of the fluiddetected by the second temperature detector 429 is indicated by atemperature display 431.

The line heater 435 placed out of the tubes 401a and 401b prevents thefluid, heated by the fluid heater 400, from being cooled down whilebeing introduced into other devices, such as a thin film fabricatingdevice or a thin film etching device, the line heater 435 beingconnected with the plate heaters 419. Temperatures and on/off states ofthe line heater 435 and the plate heaters 419 are controlled by a secondtemperature controller 439 and a second power controller 437.

Further, a high temperature valve 441 which is heatresisting is providedin the discharge tube 401b connected to the fluid heater 400 and aclose/open condition of the high temperature valve 441 is determined bya signal which is detected by the second temperature detector 429. Whenthe temperature detected by the second temperature detector 429 is overan objective temperature, for example, a temperature at about 600°C.,the main system control device 433 transmits a signal to the hightemperature valve 441, which opens its valve to discharge the fluid inthe fluid heater 400 into a semiconductor device fabricating apparatus.While, when the temperature detected by the second temperature detector429 is below the objective temperature, the main system control device433 controls the high temperature valve 441 to close its valve until thefluid is sufficiently heated up to the objective temperature andsupplies a command signal to the first temperature controller 427 toincrease the temperature of the main heater 411. The first temperaturecontroller 427, which receives the command to increase the temperatureof the main heater 411 from the main system control device 433, suppliesa signal to the first power controller 423 to increase the power volumeapplied to the main heater 411. Thus, the first power controller 423increases the power volume applied to the main heater 411 in accordancewith the signal outputted from the first temperature controller 427, andthe temperature of the main heater 411 increases in accordance with theincreased power volume, the increased temperature being detected by thefirst temperature detector 429.

With reference to FIGS. 5 through 9, each unit of the fluid heateraccording to the present invention in FIG. 4 will now be described indetail.

FIGS. 5A and 5B illustrate the main heater 411 of the transparent tube409. The main heater 411 is formed of the helical conductor havingvarious radii in sequence, for example, a long radius, followed by amedium radius, and then a small and the its pattern repeating itself.

In FIG. 5A, directions of arrows indicate the flow of the fluids. Thatis, the main heater is helically formed having the different radii, sothat the fluids evenly contact the heater and thus are well mixed witheach other, which results in improvement of the temperature uniformityof the fluids. Also, since the heater is formed in the helical type, acontact area between the fluid and the heater enlarges, therebyincreasing the heat efficiency of the heater. FIG. 5B is a plan view ofthe FIG. 5A.

FIG. 6 illustrate the transparent tube 409, the main heater 411 and thesupport 407. As shown therein, transparent tube holes 409a are formed atan lower portion of the transparent tube 409, so that the fluid heatedby the main heater 411 is discharged out of the transparent tube 409through the transparent tube holes 409a as in the directions of arrows,which indicate the flow direction of the fluid.

FIG. 7 is a side view of the internal vessel 405. As shown therein,there are internal vessel holes 405a formed at an upper portion of theinternal vessel 405, so that the fluid is discharged out of the internalvessel 405 through the internal vessel holes 405a as in the directionsof arrows, which indicate the flow direction of the fluid.

FIG. 8A illustrates the external vessel 403 and the is external heater413 surrounding the external vessel 403 in the horizontal direction,wherein the heat shield material 421 is disposed at the outer side ofthe external heater 413. In FIG. 8B, the external vessel 403 and theexternal heater 413 are illustrated, the external heater 413 beingvertically disposed at the outer wall of the external vessel 403.

Now, an operation effect of the thusly constructed fluid heater will beexplained with the accompanying drawings.

The gases in the fluid state flow into the transparent tube 409 of thefluid heater 400 according to the present invention through the inflowtube 401a, and the fluid introduced into the transparent tube 409contacts the main heater 411 in the transparent tube 409, thus beinginitially heated. Here, the fluid in the transparent tube 409 flows froman upper part to a lower part thereof, thus being heated by receivingthe heat from the main heater 411. More specifically, the fluid, heatedby the vortex which is formed while the fluid passes through the gap ofthe heater, mixes well, thus being evenly heated. As shown in FIG. 1,the inside of the transparent tube 409 is a first zone Z1. The fluidheated in the first zone Z1 is discharged to a second zone Z2 throughthe transparent tube holes 409a of the lower portion of the transparenttube 409. Here, the second zone Z2 indicates the space between theinternal vessel 405 and the transparent tube 409, as also shown inFIG. 1. The fluid flowing into the second zone Z2 is heated by thetransparent tube 409, which is secondly heated by the radiant heatsupplied from the main heater 411, and then by the support 407 formed ofthe high temperature conductor. The temperature of the heated fluid isstably maintained and transmitted through the internal vessel holes 405ato a third zone Z3, that is, the area between the external vessel 403and the internal vessel 405. In the third zone Z3, the fluid is heatedby the external heater 413 which is in a vertical or horizontal type andlocated out of the external vessel 403. The fluid heated by the externalheater 413 mixes with the process source in the vaporizer.

FIG. 9 is a schematic diagram of a fluid heater according to a secondembodiment of the present invention. As shown therein, a helical rolltube 20, described in FIGS. 2a and 2b, and a band heater 21 are disposedat a front end portion of the inflow tube 401a of the fluid heater 400,which has been described in the FIG. 4, the band heater 21 surroundingthe outer wall of the roll tube 30. Here, a heating unit consisting ofthe roll tube 20 and the heater 21 is called a first heating unit 100,and a heating unit of the fluid heater 400 shown in FIG. 4 is a secondheating unit 200. Accordingly, in the second embodiment of the presentinvention, the description of the second heating unit 200 will beomitted since the fluid heater 400 of FIG. 4 can be referred.

In the thusly constructed fluid heater according to the secondembodiment of the present invention, gases pass through the firstheating unit 100 along the tube. In the first heating unit 100, thegases are indirectly heated by a convection current heated by theexternally disposed heater and then flow into the second heating unit200. The second heating unit 200 can heat the gases at a sufficientlyhigh temperature by direct heating of the main heater in the heatingvessel disposed between the tubes, convection current heating, and heatradiance heating, and well mix the fluid by the vortex formation in themain heater, thereby obtaining the temperature uniformity. That is, inthe second embodiment of the present invention, the first heating unitis additionally disposed in the front end of the second heating unit forthereby pre-heating the fluid-state gases, so that the fluid can beheated up to the objective temperature within a short period. Also,since the fluid heater according to the second embodiment of the presentinvention heats the pre-heated fluid, the load of the heater is small,comparing to where the second heating device is only provided.

As described above, the fluid heater according to the present inventionheats the process source by heating the subsidiary gases such as thecarry gases and mixing the subsidiary gas and the process gas, therebyimproving the vaporization efficiency of the process source bypreventing previous reaction and liquefaction of the process source.

Also, by employing the in-line type heater in which the helical mainheater is provided, the uniformity of the fluid temperature is improved,thereby obtaining a thin film of a high quality, which results in theimprovement of the reliability of the semiconductor device. In addition,since the internal vessel and the transparent tube are disposed in theexternal vessel, the fluid, which is previously heated by the directcontact with the main heater, is once more heated by indirect heatingthrough the tube wall and the support, thereby improving the heatefficiency of the main heater and quickly increasing the fluidtemperature.

Further, the fluid heater according to the present invention is designedsuch that the fluid flows from the top to the bottom of the transparenttube, then from the bottom to the top of the internal vessel, and thenfrom the top to the bottom of the external vessel, thus the flow path ofthe fluid lengthens even in the small space, comparing to theconventional art, thereby having an effect of efficiently heating thesemiconductor gas.

Lastly, since the fluid is heated by the first and second heating units,there is no need to excessively supply the power to either heaters. Thatis, since the fluid can be sufficiently heated up to the objectivetemperature with small volume of the power, the load to the heater canbe reduced.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the fluid heater for thesemiconductor device of the present invention without departing from thespirit or scope of the invention. Thus, it is intended that the presentinvention cover the modifications and variations of this inventionprovided they come within the scope of the appended claims and theirequivalents.

What is claimed is:
 1. A fluid heater for a semiconductor device,comprising:an external vessel (401), a bottom of which is connected witha discharge tube (406) of a fluid or a gas; a high temperature valve(441) provided in a predetermined portion of the discharge tube (401b);an internal vessel (405) disposed being distanced from an inner wall andthe bottom of the external vessel (403) to have a space where the fluidflows in the external vessel (403), the internal vessel (405) having aplurality of internal vessel holes (405a) at an upper portion thereof; atransparent tube (409) disposed being distanced from an inner wall ofthe internal vessel (405) to have a space where the fluid flows in theinternal vessel (405), the transparent tube (409) having a plurality oftransparent tube holes (409a) at a lower portion thereof; a detachableflange (415), one side of which is in contact with the external vessel(403), the internal vessel (405) and the transparent tube (409); a fluidinflow tube (401a)connected with the other side of the flange (415); amain heater (411) provided in the transparent tube (409) and formed of athermal conductor in a helical type the radius of which varies; and anexternal heater (413) disposed at an outer wall of the external vessel(403).
 2. The fluid heater according to claim 1, wherein a heat shieldmaterial (421) surrounds the external vessel (403) in whole and thetransparent tube (409).
 3. The fluid heater according to claim 2,wherein a plate heater (419) is disposed between the heat shieldmaterial (421) and an upper surface of the flange (415).
 4. The fluidheater according to claim 2, wherein a line heater (435) is disposedbetween the heat shield material (421) and the transparent tube (409).5. The fluid heater according to claim 1, wherein a support (407) whichis refractory and has high thermal conductivity is placed between abottom of the internal vessel (405) and a lower portion of thetransparent tube (409).
 6. The fluid heater according to claim 5,wherein the support (407) is formed of ceramic.
 7. The fluid heateraccording to claim 1, wherein the transparent tube (409) is formed ofquartz which is transparent and has high thermal conductivity.
 8. Thefluid heater according to claim 1, wherein the external heater (413) ishorizontally disposed at a circumference of the external vessel (403).9. The fluid heater according to claim 1, wherein the external heater(413) is vertically disposed at a circumference of the external vessel(403).
 10. The fluid heater according to claim 1, wherein a firsttemperature detector (425) for detecting a temperature of the mainheater (411) is connected with a main heater terminal (412) whichsupplies the power to the main heater (411), the first temperaturedetector (425) being connected with a first temperature controller (427)in which there is provided a first power controller (423) which isconnected to the main heater terminal (412),a second temperaturedetector (429) for detecting a temperature of the fluid before beingdischarged out of the external vessel (403) is disposed between thebottom of the external vessel (403) and the bottom of the internalvessel (405), a temperature display (431) displaying a temperature ofthe fluid detected by the second temperature detector (429) is disposedout of the external vessel (403), a main system controller (433)connected with the temperature display (431) commands the hightemperature valve (441) to open its valve when the temperature displayedby the temperature display (431) is above an objective temperature andclose its valve when the displayed temperature is below the objectivetemperature and commands the first temperature controller (423) toincrease the temperature of the main heater (411).
 11. The fluid heateraccording to claim 1, wherein a helical roll tube (20) is connected withan front end portion of the tube (409) at the fluid inflow sideconnected to the flange (415) and a band heater (21) surrounds the rolltube (20).